The long-term goal of this K23 application is to improve our understanding of how auditory capacity drives speech and language development in deaf infants who use cochlear implants (CIs). As a pediatric otolaryngologist and CI surgeon, the candidate is intimately aware of the wide variability in clinical outcomes in this population and the need for more precise clinical tools for assessing benefit and predicting speech and language outcomes in CI infants. As a first step, this research plan will investigate CI infants' early acquisition of auditory spectral and temporal resolution using behavioral methods. Spectral ripple discrimination (SRD) and amplitude modulation detection are two measures that are independent predictors of speech perception skills in adults with CIs. The central hypothesis of this application is that spectral and temporal resolution will each reach maturity in CI infants over the first seven months after implantation and will constrain subsequent acquisition of speech perception and language skills. The basis for this hypothesis is that spectral and temporal resolution of the normal auditory system mature during the first year of life, reflecting early development of cochlear and brainstem neural mechanisms. Evidence suggests that these early developing structures also mature rapidly in CI infants during the first post-implant year. The rationale for the proposed research is that improving our understanding of how spectral and temporal skills emerge and relate to spoken-language acquisition in CI infants will enable the development of clinical measures of auditory capacity in CI infants. The infant psychoacoustic methods described in this K23 application will form the core an ongoing research program to study auditory development in CI infants. Local coursework and training experiences in the fields of auditory development, speech and language development, and electrophysiology will enable the PI to continue to build the skill set necessary to translate basic psychoacoustic research findings into clinically feasible measures. This career development and research plan, conducted within an extremely supportive and nurturing academic environment will set the candidate up to succeed as a sustainably funded investigator overseeing this clinically relevant program of research.